High-speed short-stroke forging press

ABSTRACT

At least one press ram is mounted and guided in a machine frame for a straight-line movement relative thereto. Helical drive means are carried by said machine frame and operatively connected to said press ram and operable to adjust the stroke position of said press ram and axially to reciprocate said press ram.

United States Patent 1 1 Kralowetz Dec. 30, 1975 HIGH-SPEED SHORT-STROKE FORGING 2,905,031 9/1959 Appel et al. 72/452 PRESS 3,119,507 [/1964 Burritt 72/452 3,589,278 6/l97l Brauer 72/454 Inventor: Bruno Kralowell, Ulrich 3,785,282 1 1974 Kamelander 74 25 x Steyr, Austria 3,834.2]4 9/1974 Kralowetz 72/452 Filed: Oct. 1974 3,842,652 10/1974 Yonezawa 72/454 [211 App! 5l601o Primary Examiner-C. W. Lanham Assistant Examiner-Joseph A. Walkowski [30] Foreign Application Priority Data Attorney. g Firm-Kurt Kelmafl Nov. 15, I973 Austria 9603/73 52 US. (:1. 72/402; 72/452; 72/454; [57] ABSTRACT 2 74/25; At least one press ram is mounted and guided in a ma- [Sl] Int. Cl. B21. chine frame f a straighpline movement relative Field of Search-mm /2 thereto. Helical drive means are carried by said ma- 39-16 chine frame and operatively connected to said press ram and operable to adjust the stroke position of said Releremes Cited press ram and axially to reciprocate said press ram.

UNITED STATES PATENTS 429,701 6/1890 Parmelee 72 454 5 9 Dm'mg Figures 20' 2 3 20 a you 0/ 1%} II U.S. Patent Dec. 30, 1975 Sheet 2 of5 3,929,000

=E" c: I

li o r I a- H L I I! mm v U.S. Patent Dec. 30, 1975 Sheet 3 of5 3,929,000

U.S. Patent Dec. 30, 1975 Sheet 4 of5 3,929,000

U.S. Patent Dec. 30, 1975 Sheet 5 of 5 FIG. 9

HIGH-SPEED SHORT-STROKE FORGING PRESS This invention relates to a high-speed short-stroke forging press which comprises at least one press rarn, which is guided along a straight line in the machine frame and the stroke position of which is adjustable by helical drive means.

The previously known forging presses are generally provided with hydraulic or eccentric drive means for reciprocating their press rams. Whereas the stroke position of the press rams may be adjusted in a relatively simple manner by the helical drive means provided for this purpose, expensive drive means, which have considerable disadvantages, are required for the actual working motion. For instance, a hydraulic drive involves a large hydraulic compliance due to the com pressibility of the hydraulic fluid and the elasticity of the conduits. An eccentric drive requires machine elements, such as crankshafts and eccentric shafts, large transmissions and the like and these can be made only at considerable expense. Both drive means have also the particularly inconvenient drawback that the substantial hydraulic or mechanical means required necessitate a large and also heavy machine frame of the forging press. The weight of said machine frame renders the installation of the machine rather difficult and owing to its large size the machine frame is subjected to considerable elongation by strong forging forces. It will be understood that such elongation could be taken up by the provision of reinforced tie rods in the machine frame but this would involve an increase in the weight and cost of the machine frame.

It is an object of the invention to eliminate these disadvantages and to provide a forging press which is of the kind described first hereinbefore and in which the press ram is driven by means which are simple and compact and can be manufactured at low cost so that the machine may comprise a frame which is correspondingly small and light in weight.

This object is essentially accomplished according to the invention in that helical drive means are provided also for reciprocating the press ram. Because in the forging press according to the invention, strictly mechanical drive means are used for adjusting the stroke position of the press ram and for reciprocating said ram, there will be no difficulties as regards the cushioning, and because the machine elements required to drive the press ram consists mainly of turned elements and only very simple transmissions are required, etc., the manufacture of the forging press according to the invention is much simpler and less expensive than the manufacture of the known forging presses. The most significant advantage afforded by the invention resides in the fact that the forging press may be rather compact because the helical drive means for reciprocating the press ram require relatively little space. The forging forces exerted may be transmitted to the machine frame fairly close to the forging axis so that those parts of the machine frame which are stressed in tension during the forging operation are not too long and the resulting elongations are small for the same reason. As a result, for given maximum elongations, the machine frame of the forging machine according to the invention may be much smaller than in the previous forging presses so that the overall weight of the machine may be considerably reduced. On the other hand, if a machine frame is used which has the same dimensions, the elongations of the frame will be correspondingly re 2 duced. Comprising helical drive means for adjusting the stroke position of the press ram and for reciprocating said ram, the forging press according to the invention permits of an improved overall design owing to the more favorable transmission of forces in the machine frame.

According to a particularly preferred feature of the invention, the drive means for reciprocating the press ram comprises a cam ring, which is fixed in the machine frame, and a cam follower, which is resiliently urged against the cam ring and is angularly oscillatable preferably by means of a transverse lever, the end faces of the cam ring and of the cam follower being forced against each other and cooperating like clutch jaws having helical faces. in this arrangement, the cam ring and the cam follower have helical faces contacting each other so that a rotation of the cam follower relative to the non-rotatable cam ring will result in an axial displacement of the cam follower. The latter is resiliently biased toward the cam ring so that the jaw faces which contact at a time do not disengage. Because obviously the cam follower is axially slidably mounted in the machine frame and is connected to the press ram, an angular oscillation of the cam follower at a suitably high frequency will reciprocate the press ram at the desired stroke frequency. The means provided according to the invention for reciprocating the press ram are very simple and compact and involve no problems.

Because during a rotation of the cam follower, the helical jaw faces impart an axial movement to the cam follower and to the press ram only in one direction, toward the workpiece, a spring element or the like which is stressed during the forward movement of the cam follower must be provided to effect the return movement. The specific nature of this spring element is not essential. Within the scope of the invention, the cam follower is adapted to be pneumatically forced against the cam ring so that the air cushion which biases the cam follower serves as a spring element. This arrangement has the advantage that the pressure of the air cushion may be regulated to adjust not only the contact pressure force but also the compliance in view of various requirements.

According to another feature of the invention, the press ram is held against rotation and is rotatably connected to a coaxial drive screw, which is angularly oscillatable by a transverse lever and has a screwthreaded portion in threaded engagement with internal screw threads of a guide bushing, which is axially fixed and non-rotatable or adapted to be held against rotation. When the drive screw is angularly oscillated, the fixed guide bushing compels the screw to perform an axial reciprocating motion, which is transmitted to the press ram. The extent of the reciprocating motion is determined by the lead of the coarse external and internal screw threads and by the angle through which the transverse lever is oscillated. Besides, the pressure force which can be applied by the press ram is increased by the mechanical advantage of the drive means. This mechanical advantage depends on the power screw and the length of the transverse lever.

It will be particularly desirable if the transverse lever is formed with a cam slot for guiding a slider, which is rotatably mounted on a drive eccentric, because the angular oscillation can be most simply imparted to the transverse lever by such an arrangement.

According to another embodiment of the invention, the press ram carries external screw threads, which are in threaded engagement with an adjusting nut, which is fixed in a connecting sleeve, which is mounted to be rotatable relative to the drive screw and cam follower and axially non-displaceably coupled thereto, and said adjusting nut is adapted to be driven by a gear, particu larly a worm wheel, which is non-rotatably connected to the connecting sleeve and axially slidable relative thereto. The connection of the drive screw and cam follower to the connecting sleeve permits of a simple justaposed arrangement of the helical drive means provided for the reciprocating motion and for adjusting the stroke position. To adjust the stroke position, the gear is used to rotate the connecting sleeve and the adjusting nut so that the press ram is axially displaced because the adjusting nut and connecting sleeve are held in position by the nonmoving drive screw and the cam follower. As a result, a relative rotation between the press ram and the adjusting nut results in an axial movement of the press ram. When the gear is non-moving, the reciprocating motion can be imparted to the press ram by the angular oscillation of the drive screw in the guide bushing or of the follower relative to the cam ring. in that case the connecting sleeve does not follow the rotational movements of the drive screw and of the cam follower because it is held against rotation by the non-moving gear. The connecting sleeve can perform only the reciprocating motion because the gear is axially slidably mounted on the connecting sleeve.

To ensure a firm holding of the guide bushing in the machine frame, it is a feature of the invention that the guide bushing for the drive screw has a parallelepipedic external shape and is directly embedded in the machine frame. Because the forging forces are transmitted from the press ram via the drive screw and the guide bushing to the machine frame, the guide bushing must be particularly firmly held in the machine frame, particularly against rotation. This is ensured by the non-circular external shape of the bushing.

According to a further preferred feature of the invention the guide bushing is rotatable and is formed with the internal screw threads in threaded engagement with the drive screw and is received by an adjusting sleeve, which is rotatably mounted in the machine frame and adapted to be driven, and the drive screw is rotatable relative to the press ram and axially non-displaceably connected thereto and has an axial play. This arrangement results in a combination of the drive means for imparting the reciprocating motion and the drive means for adjusting the stroke position so that an even more compact forging press can be designed. In this case the guide bushing serves also as an adjusting nut for adjusting the stroke position so that the drive means for imparting both motions required can be accommodated within very small space. To adjust the stroke position, the adjusting sleeve and the guide bushing are rotated to change the position of the press ram because the adjusting sleeve is rotatably mounted in the machine frame but is non-displaceable. During the reciprocating motion, the non-moving adjusting sleeve prevents a rotation and displacement of the guide bushing so that the press ram performs the corresponding working stroke and the forces occurring cana be transmitted by the adjusting sleeve into the machine frame. Because in this embodiment the drive screw is axially nondisplaceable relative to the press ram, the drive 4 screw must follow the axial movement of the press ram during its reciprocating motion and during the adjustment of its stroke position and for this purpose the drive screw must have a sufficiently large axial play.

Because all forces loading the press ram must be transmitted to the machine frame through the adjusting sleeve, the means for driving the latter must withstand the loads which occur. For this reason it is a feature of the invention that the adjusting sleeve is provided with an adjusting arm, which cooperates with a coupling member, which is movable transversely to the axis of the adjusting sleeve by a screw. In spite of the required rotatibility, this arrangement can take up without difficulty the torques exerted on the adjusting sleeve.

In a forging press having more than one press ram, it is a feature of the invention in that common or synchronized drive means are provided for the helical drive means for the reciprocating motion and common or synchronized drive means are provided for the helical drive means for adjusting the stroke position so that the respective movements are exactly synchronized.

In forging presses having four press rams spaced apart it is a particularly desirable feature of the invention that the pairs of transverse levers connected to the drive screws and/or cam followers are provided with forked end portions, which extend toward each other and are angled through 45 and the fork portions of said end portions form the cam slots for the associated sliders, which are mounted on parallel eccentric shafts extending normal to the fork plane. These angled transverse levers permit of a compact design and in spite of the fact that the axes of the press rams extend at right angles to each other these transverse levers enable the use of parallel eccentric shafts, which can be driven by simple spur gear trains.

Three embodiments of the invention are shown diagrammatically and by way of example on the accompanying drawings, in which FIGS. 1 to 3 are, respectively, a longitudinal sectional view, a top plan view, and a sectional view taken on line lll-lll in FlG. 1 and show a two-ram forging press according to the invention,

FIGS. 4 to 6 are, respectively, a transverse sectional view, a side elevation, and a sectional view taken on line Vl-Vl in FIG. 4 and show a four-ram forging press, and

FIGS. 7 to 9 are, respectively, a longitudinal sectional view, a sectional view taken on line VlIlVlll in FIG. 7, and an enlarged detail elevation and show a special design of the drive means for reciprocating the ram.

The crux of the invention resides in that high-speed short-stroke forging presses comprise helical drive means for adjusting the stroke position of the press ram and helical drive means for reciprocating the ram. The design of these helical drive means will depend on the required dimensions of the machine, the forging forces which are required, the number of press rams, etc. Three possible embodiments are shown in the drawings. in accordance with FIGS. 1 to 3, two press rams 2 are horizontally guided by means of sliding-surface bearings 3 in a machine frame 1. The rams 2 are held against rotation by locking means 5, which engage a guide groove 4. Each press ram 2 has a screw-threaded portion 6 provided with external screw threads 7 in threaded engagement with an adjusting nut 8. The latter is fixed in a connecting sleeve 9, which is adapted to be driven by a worm wheel 10, which is non-rotatably connected to the connecting sleeve 9 and axially slidable thereon. The connecting sleeve 9 is guided ir suitable sliding-surface bearings 11 in the machine frame 1 and connects the press rams 2 to a drive screw 12, on which the connecting sleeve 9 is rotatable but is axially fixed thereto. The drive screw 12 is rotatably and longitudinally slidably mounted in sliding surface bearings 13 in the machine frame 1 and has a screwthreaded portion 14 in threaded engagement with internal screw threads of a guide bushing 15. The latter has a parallel-epipedic external shape and is directly embedded in the machine frame so that the guide bushing can take up high loads and transmit them to the machine frame. The drive screw is connected to a transverse lever 16, which is formed with a cam slot 17 for a slider 18, which is rotatably mounted on a drive eccentric 19. The latter is rotated by a spur gear train 20 so that the slider 18 imparts an angular oscillation to the transverse lever 16 and to the drive screw 12, which is thus caused to perform an axial reciprocation because its screw-threaded portion 14 is moved in the stationary internal screw threads of the guide bushing 15. This alternating longitudinal motion is transmitted to the press ram, which reciprocates at the desired stroke frequency, which depends on the speed of the drive eccentric. The reciprocation of the drive screw is transmitted to the press ram by the connecting sleeve 9 and the adjusting nut 8. In this operation, only the drive screw is rotated whereas the connecting sleeve and press ram are merely reciprocated. When it is desired to adjust the stroke position, the drive screw 12 is nonmoving and the conducting sleeve 9 is rotated by the worm wheel 10. Because the locking means prevent a rotation of the press ram and the adjusting nut 8 is now rotated relative to the screw-threaded portion 6 of the press ram 2, the latter is axially displaced relative to the drive screw and thus changes its stroke position, i.e., its distance from the axis of the workpiece. The drive means for reciprocating both press rams 2 include a common motor 20', which by a transmission shaft 20" drives the two spur gear sets 20 for driving the drive eccentrics 19. The stroke positions of both press rams are also adjusted in unison because the two worm wheels for driving the connecting sleeves 9 mesh with corresponding worms 10', which are also driven in unison by a common transmission shaft 10". These common drive means for both press rams and the synchronization of the press ram motions ensure that the drive means for both press rams will be exactly synchronized.

FIGS. 4 to 6 show a short-stroke forging press according to the invention, which comprises four press rams 21, which are spaced 90 apart and are guided along straight lines in a suitable machine frame 22 and held against rotation by suitable locking means 23. These press rams 21 are directly connected to a drive screw 24 and are rotatable and axially fixed relative thereto. A screw-threaded portion 25 of each drive screw 24 is in threaded engagement with the internal screw threads of a guide bushing 26, which is received by an adjusting sleeve 27. The latter is rotatably mounted in the machine frame 22 and is angularly movable by an adjusting arm 28, which cooperates with a coupling member 29. The latter is carried by a screw 30, which is adapted to be rotated by a worm wheel 31. In response to a rotation of the screw 30, the coupling member 29 reciprocates in the axial direction of the screw 30 thus imparts an angular movement to the adjusting arm and the adjusting sleeve. Because the guide bushing 26 is fixed to the adjusting sleeve, an angular movement of the latter will be transmitted to the guide bushing so that the stroke position of the press rams 21 is adjusted. For the reciprocating motion, an angular oscillation is imparted to the drive screw 24 by the transverse lever 32 and is transformed into an axial reciprocation of the press rams by the internal screw threads of the guide bushing when the guide bushing and the adjusting sleeve are non-moving. Because the drive screws 24 must be axially moved together with the press rarns 21 for an adjustment of the stroke position, the drive screws must have sufficient play in that direction. The transverse levers 32 are driven by eccentrics 33, on which sliders 34 are mounted, which are guided in the transverse levers. For a simple and compact design, pairs of transverse levers 32 have forked end portions 35, which extend toward each other and are angled through 45. The fork portions form cam slots for the sliders 34. Owing to the provision of the angled transverse levers 32, the drive eccentrics 33 may be parallel to each other so that each pair of eccentrics can be driven in unison by a simple spur gear train 36. It will be understood that cylindrical guide surfaces are required between the sliders 34 and the fork portions of the transverse levers so that the motion of the eccentrics can be satisfactorily transmitted to the drive screws in spite of the fact that the transverse levers 24 are angled. ln this embodiment the drive means for reciprocating the press rams are synchronized or driven by common motors and so are the drive means for adjusting the stroke position. For instance, the reciprocation of each pair of press rams derived from a common motor 37, which is synchronized with the motor for driving the other pair of press rams. Common, synchronized drive means 38 are provided for adjusting the stroke positions of the several press rams.

FIGS. 7 to 9 show special drive means according to the invention for reciprocating the press ram. These drive means comprise a cam ring 40 fixed in the machine frame 31 and a cam follower 41, which is mounted to be rotatable and axially displaceable. The end faces 42, 43 of the cam ring and cam follower cooperate like the members of a jaw clutch, the jaws of which have helical contacting faces 44, 45. The cam follower is connected to a piston 46, which is guided in a cylinder 47, which is carried by the machine frame 39. Compressed air or the like is supplied to the piston 46 in such a manner that the compressed air cushion formed in the cylinder chamber 48 constantly forces the cam follower 41 against the cam ring 40. To reciprocate the press ram, an angular oscillation is imparted to the cam follower by means of the transverse lever 49. For this purpose, the latter is formed with a cam slot 50 for a slider 51, which is rotatably mounted on an eccentric 54, which is adapted to be driven by a motor 53 through a spur gear train 52. Owing to the helical jaw faces 44, 45 of the cam follower 41 and cam ring 40, a rotation of the cam follower relative to the cam ring in the direction in which the jaw faces rise will result in an axial thrust, which moves the cam follower away from the cam ring. As a result, the piston 46 is also displaced so that the pressure in the air cushion in the cylinder chamber 48 is increased and during the reverse rotation of the cam follower the latter is returned by the expanding air cushion and the jaw faces are always in contact with each other. The press ram is coupled by a connecting sleeve 55 to the cam follower 41 and is reciprocated at adesired stroke frequency in response to an angular oscillation of the cam follower at a sufficiently high frequency. The press ram, not shown, is non-rotatably guided in the machine frame and is axially displaceable relative to the connecting sleeve 55 to permit of an adjustment of the stroke position. The connecting sleeve is rotatable relative to the cam follower and axially fixed thereto.

What is claimed is:

l. A high-speed short-stroke forging press, which comprises a machine frame at least one press ram mounted and guided in said machine frame for a straight-line movement relative thereto, and helical drive means carried by said machine frame and operatively connected to said press ram and operable to adjust the stroke position of said press ram and axially to reciprocate said press ram, and in which helical drive means comprise a cam ring fixed in said machine frame and formed on one side with helical cam faces, a cam follower mounted in said machine frame for angular and axial movement relative to said cam ring and having helical faces which face said helical cam faces, biasing means for resiliently urging said helical faces of said cam follower against said helical cam faces, and means for angularly oscillating said cam follower, said cam follower being axially fixed to said press ram and adapted to reciprocate the same.

2. A forging press as set forth in claim 1, which comprises a transverse lever for angularly oscillating said cam follower.

3. A forging press as set forth in claim 2, which comprises a drive eccentric,

a slider rotatably mounted in said eccentric, and

a cam slot formed in said transverse lever and in guiding engagement with said slider.

4. A forging press as set forth in claim 1, in which said biasing means are pneumatically operable.

5. A high-speed short-stroke forging press comprising 1. a machine frame, 2. four press rams spaced apart, the press rams being mounted and guided in the machine frame for a straight-line movement relative thereto,

3. a first helical drive means and a second helical drive means for each of the press rams, the helical drive means being carried by the machine frame and operatively connected to a respective one of the press rams, the helical drive means being operable to adjust the stroke position of the press rams and axially to reciprocate the press rams, and the helical drive means for each press ram including a. a transverse lever which is angularly oscillatable to operate the respective helical drive means, the transverse levers being arranged in pairs and having end portions angled through 45 and extending toward each other, and having forked portions extending in a plane and formed with cam slots,

b. a cam ring fixed in the machine frame and formed on one side with helical cam faces,

c. a cam follower mounted in the machine frame for angular and axial movement relative to the cam ring and connected to one of the transverse levers, and having helical faces which face the helical cam faces, and

d. biasing means for resiliently urging the helical faces of the cam follower against the helical cam faces,

4. parallel eccentric shafts mounted in the machine frame and extending normal to the plane in which the forked portions of the transverse levers extend,

and

. sliders mounted on the eccentric shafts and in guided engagement with the cam slots.

l I l 0 

1. A high-speed short-stroke forging press, which comprises a machine frame at least one press ram mounted and guided in said machine frame for a straight-line movement relative thereto, and helical drive means carried by said machine frame and operatively connected to said press ram and operable to adjust the stroke position of said press ram and axially to reciprocate said press ram, and in which helical drive means comprise a cam ring fixed in said machine frame and formed on one side with helical cam faces, a cam follower mounted in said machine frame for angular and axial movement relative to said cam ring and having helical faces which face said helical cam faces, biasing means for resiliently urging said helical faces of said cam follower against said helical cam faces, and means for angularly oscillating said cam follower, said cam follower being axially fixed to said press ram and adapted to reciprocate the same.
 2. A forging press as set forth in claim 1, which comprises a transverse lever for angularly oscillating said cam follower.
 2. four press rams spaced 90* apart, the press rams being mounted and guided in the machine frame for a straight-line movement relative thereto,
 3. a first helical drive means and a second helical drive means for each of the press rams, the helical drive means being carried by the machine frame and operatively connected to a respective one of the press rams, the helical drive means being operable to adjust the stroke position of the press rams and axially to reciprocate the press rams, and the helical drive means for each press ram including a. a transverse lever which is angularly oscillatable to operate the respective helical drive means, the transverse levers being arranged in pairs and having end portions angled through 45* and extending toward each other, and having forked portions extending in a plane and formed with cam slots, b. a cam ring fixed in the machine frame and formed on one side with helical cam faces, c. a cam follower mounted in the machine frame for angular and axial movement relative to the cam ring and connected to one of the transverse levers, and having helical faces which face the helical cam faces, and d. biasing means for resiliently urging the helical faces of the cam follower against the helical cam faces,
 3. A forging press as set forth in claim 2, which comprises a drive eccentric, a slider rotatably mounted in said eccentric, and a cam slot formed in said transverse lever and in guiding engagement with said slider.
 4. A forging press as set forth in claim 1, in which said biasing means are pneumatically operable.
 4. parallel eccentric shafts mounted in the machine frame and extending normal to the plane in which the forked portions of the transverse levers extend, and
 5. sliders mounted on the eccentric shafts and in guided engagement with the cam slots.
 5. A high-speed short-stroke forging press comprising 